Exercise - Deploy an application on your Azure Kubernetes Service cluster

In this exercise, deploy your company's website as a test app onto Azure Kubernetes Service (AKS). The website is a static website with an underlying technology stack of HTML, CSS, and JavaScript. It doesn't receive as many requests as the other services and provides us with a safe way to test deployment options.

Create a deployment manifest

You create a deployment manifest file to deploy your application. The manifest file allows you to define what type of resource you want to deploy and all the details associated with the workload.

Kubernetes groups containers into logical structures called pods, which have no intelligence. Deployments add the missing intelligence to create your application. Let's create a deployment file.

1. On your computer, use a text editor like Visual Studio Code, and copy and paste the following YAML code into a file named deployment.yaml and save the file.

   # deployment.yaml
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: contoso-website
   spec:
     selector:
       matchLabels:
         app: contoso-website
     template:
       metadata:
         labels:
           app: contoso-website
       spec:
         nodeSelector:
           kubernetes.io/os: linux
         containers:
           - image: mcr.microsoft.com/mslearn/samples/contoso-website
             name: contoso-website
             resources:
               requests:
                 cpu: 100m
                 memory: 128Mi
               limits:
                 cpu: 250m
                 memory: 256Mi
             ports:
               - containerPort: 80
                 name: http
   

   • Two keys are used to define the apiVersion and kind of manifest you're creating. For more information about apiVersion and what values to put in this key, see the official Kubernetes deployments documentation.
   • The name is the name of the deployment. Use it to identify and query the deployment information when you use kubectl.
   • The template definition defines the pod information within the manifest file. The template is placed in the manifest file under the deployment specification section.
   • The labels key to allow deployments to find and group pods.
   • In an AKS cluster that has Linux and Windows node pools, the deployment manifest defines a nodeSelector to tell your AKS cluster to run the sample application's pod on a node that can run Linux containers. Linux nodes can't run Windows containers and vice versa.
   • The containers key is an array of container specifications because a pod can have one or more containers. The specification defines an image, a name, resources, ports, and other important information about the container. All running pods follow the name contoso-website-<UUID>, where UUID is a generated ID to identify all resources uniquely.
   • It's a good practice to define a minimum and a maximum amount of resources that the app is allowed to use from the cluster. You use the resources key to specify this information. The resource section allows you to specify the minimum resource amount as a request and the maximum resource amount as a limit.
   • The ports this container exposes externally through the ports key. The ports key is an array of objects, which means that a container in a pod can expose multiple ports with multiple names. You name the port by using the name key. Naming ports allows you to change the exposed port without changing files that reference that port.

2. Upload deployment.yaml to your Cloud Shell session by selecting Manage files > Upload.

Apply the manifest

1. In Cloud Shell, run the kubectl apply command to submit the deployment manifest to your cluster.

   kubectl apply -f ./deployment.yaml
   

   The command should output a result similar to the following example.

   deployment.apps/contoso-website created
   

2. Run the kubectl get deploy command to check if the deployment was successful.

   kubectl get deploy contoso-website
   

   The command should output a table similar to the following example.

   NAME              READY   UP-TO-DATE   AVAILABLE   AGE
   contoso-website   1/1     1            1           19s
   

3. Run the kubectl get pods command to check if the pod is running.

   kubectl get pods
   

   The command should output a table similar to the following example.

   NAME                               READY   STATUS    RESTARTS   AGE
   contoso-website-1c2b3b4b5b-dzsvm   1/1     Running   0          68s